CN110797880A - Active harmonic filter and regenerative energy control device and method of operating the same - Google Patents

Active harmonic filter and regenerative energy control device and method of operating the same Download PDF

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Publication number
CN110797880A
CN110797880A CN201910652610.2A CN201910652610A CN110797880A CN 110797880 A CN110797880 A CN 110797880A CN 201910652610 A CN201910652610 A CN 201910652610A CN 110797880 A CN110797880 A CN 110797880A
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China
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ahf
inverter
rec
asd
mode
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CN201910652610.2A
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Chinese (zh)
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H·李
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Eaton Intelligent Power Ltd
Eaton Corp
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Eaton Corp
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P29/00—Arrangements for regulating or controlling electric motors, appropriate for both AC and DC motors
    • H02P29/50—Reduction of harmonics
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/18—Arrangements for adjusting, eliminating or compensating reactive power in networks
    • H02J3/1821—Arrangements for adjusting, eliminating or compensating reactive power in networks using shunt compensators
    • H02J3/1835—Arrangements for adjusting, eliminating or compensating reactive power in networks using shunt compensators with stepless control
    • H02J3/1842—Arrangements for adjusting, eliminating or compensating reactive power in networks using shunt compensators with stepless control wherein at least one reactive element is actively controlled by a bridge converter, e.g. active filters
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/01—Arrangements for reducing harmonics or ripples
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/12—Arrangements for reducing harmonics from ac input or output
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/44—Circuits or arrangements for compensating for electromagnetic interference in converters or inverters
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
    • H02M7/5387—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration
    • H02M7/53871—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P27/00—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage
    • H02P27/04—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage
    • H02P27/06—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters
    • H02P27/08—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters with pulse width modulation
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/42—Circuits or arrangements for compensating for or adjusting power factor in converters or inverters
    • H02M1/4208—Arrangements for improving power factor of AC input
    • H02M1/4283—Arrangements for improving power factor of AC input by adding a controlled rectifier in parallel to a first rectifier feeding a smoothing capacitor
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M5/00—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases
    • H02M5/40—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc
    • H02M5/42—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters
    • H02M5/44—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac
    • H02M5/453—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M5/458—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M5/4585—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only having a rectifier with controlled elements
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
    • Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Inverter Devices (AREA)

Abstract

The invention provides an active harmonic filter and regenerative energy control device and an operation method thereof. An Active Harmonic Filter (AHF) and Regenerative Energy Control (REC) arrangement for an Adjustable Speed Drive (ASD), the AHF and REC arrangement including an inverter and a controller operatively coupled to the inverter to selectively control operation thereof. The controller is programmed to cause the inverter to operate in different modes to manage the different conditions that occur during ASD operation. In the AHF mode, the controller operates the inverter to filter out harmonics present at the input of the ASD. In the REC mode, the controller operates the inverter to control regenerative energy flowing from the ASD into the inverter.

Description

Active harmonic filter and regenerative energy control device and method of operating the same
Background
The present invention relates generally to circuits for filtering harmonics and controlling regenerative energy, and more particularly to Active Harmonic Filters (AHF) and Regenerative Energy Control (REC) devices for use with Adjustable Speed Drives (ASD) and methods of operating the same.
One type of system commonly used to perform power conversion is an adjustable speed drive (ASD, also known as a Variable Frequency Drive (VFD)). An ASD is an industrial control device that provides adjustable frequency, adjustable voltage operation for a drive system such as, for example, an Alternating Current (AC) induction motor. ASDs typically receive an AC power input, convert the AC power input to Direct Current (DC) power using a rectifier, and invert the DC power to an AC power output having a desired voltage and frequency using an inverter to control the motor. This variable operation of the ASD enables precise control of AC motor speed and torque. However, ASDs introduce harmonics into the system in which they are implemented, because ASDs are nonlinear loads.
The non-linear load introduces harmonics into the system because the waveform of the current drawn by the non-linear load does not match the sinusoidal waveform of the supply voltage. ASDs are non-linear loads because they include rectifiers that do not necessarily draw sinusoidal current and, in some cases, generate Total Harmonic Distortion (THD) when the input current is greater than 30%. Harmonic currents flowing through the system impedance produce voltage harmonics, distorting the supply voltage. Harmonic currents also increase RMS currents, introduce stress on the grid, and may damage equipment. As a result, harmonics can disrupt the proper operation of the equipment and increase the operating cost of any given system.
Different types of harmonic filters are typically used to manage the harmonics. Passive harmonic filters include capacitors, inductors, and/or resistors that provide a low impedance path for a particular harmonic frequency in order to absorb the dominant harmonic current in the system. Active harmonic filters include converters that are typically controlled using pulse width modulation. Active harmonic filters use their converters to actively monitor and control harmonic filtering. In either case, however, the harmonic filter is typically constructed as a separate driver from the ASD implementing the harmonic filter, particularly if the harmonic filter must be retrofitted to an existing ASD.
Another problem associated with ASD is the generation of regenerative energy, which is the energy returned from the motor whose inverter is running back to the ASD inverter. The electric machine will generate regenerative energy when it decelerates and a load controlled by the electric machine begins to pull the electric machine at a faster than synchronous speed, causing the electric machine to act as a generator. For example, when the elevator travels downward, its motor slows it down, producing a negative torque and thus regenerative energy. The regenerated energy is controlled using two different methods. Dynamic braking methods direct regenerative energy to a brake resistor device that dissipates the regenerative energy in the form of heat. A more preferred method of regenerative braking is to direct the regenerated energy back to the power supply or energy storage system of the electric machine. Both methods are typically performed by retrofitting the drive to an existing ASD.
While the above-described methods of filtering out harmonics and controlling the regenerated energy provide adequate solutions, these solutions are separate from each other. Therefore, in order to filter out harmonics and control regenerative energy in the existing ASD, it is necessary to install a harmonic filtering driver and a regenerative energy driver on the ASD. These two separate drives add significant cost to the use of the ASD and require additional hardware space. Thus, adding two drivers presents serious economic and design difficulties in implementing an ASD that can operate with harmonic interference and produce regenerated energy when its load is.
It is therefore desirable to design a more compact and cost effective solution to filter out harmonics in ASDs and control the regenerated energy therein.
Disclosure of Invention
Embodiments of the present invention provide a single device for actively filtering harmonics in an ASD and controlling the regenerated energy output of the ASD. The circuit can be implemented with an existing ASD as a retrofit driver.
In accordance with one aspect of the present invention, an AHF and REC apparatus for an ASD includes an inverter and a control system operatively coupled to the inverter to selectively control the operation thereof. The control system is programmed to: operating the inverter in an AHF mode to filter out harmonics present at the input of the ASD; and operating the inverter in the REC mode to control the regenerative energy flowing from the ASD into the inverter.
According to another aspect of the invention, a method of operating an AHF and REC apparatus that is coupleable to an ASD and has control thereof is performed by a controller. The method comprises the following steps: monitoring harmonics at an input of the ASD; operating the AHF and REC devices in an AHF mode to filter out harmonics; determining the flow of regenerative energy from the ASD into the AHF and REC devices; and switching operation of the AHF and REC device from the AHF mode to the REC mode to manage regenerated energy.
According to another aspect of the invention, a retrofit drive having an AHF and an REC for an ASD includes: a driver input/output capable of receiving a power input and releasing a power output; and a filter reactor having one or more inductors coupled to the driver input/output. The retrofit drive further comprises an inverter having an AC side and a DC side, wherein the AC side is coupled to the drive input/output through the reactor. The retrofit drive further comprises: a capacitor bank comprising one or more capacitors coupled to the DC side of the inverter; and a diode having a cathode and an anode, wherein the cathode is coupled to the capacitor bank. The retrofit driver further comprises a driver input coupled to an anode of the diode and capable of receiving the regenerated energy; further, the retrofit drive includes a controller configured to: operating the inverter in an AHF mode to filter out harmonics present at the input of the ASD; operating the inverter in an REC mode to regulate regenerative energy flowing into the driver input and into the anode of the diode; and deactivating the inverter in case the driver input does not receive regenerated energy and the harmonics present at the driver input/output are characterized by being below a preset threshold.
Various other features and advantages of the present invention will become apparent from the following detailed description and the accompanying drawings.
Drawings
The drawings illustrate preferred embodiments presently contemplated for carrying out the invention.
In the drawings:
fig. 1 is a schematic diagram of an electrical system including an AHF and REC device coupled to an ASD, according to one embodiment of the present invention.
Fig. 2 is a schematic diagram of an equivalent circuit of the electrical system of fig. 1 in which the inverters of the AHF and REC devices operate in an AHF mode, according to one embodiment of the present invention.
Fig. 3 is a schematic diagram of an equivalent circuit of the electrical system of fig. 1 in which the AHF and the inverter of the REC device operate in the REC mode, according to one embodiment of the present invention.
Fig. 4 is a schematic diagram of an equivalent circuit of the electrical system of fig. 1, wherein the inverters of the AHF and REC devices are in an off state.
Fig. 5 is a flow diagram illustrating a technique for controlling the AHF and REC apparatus of fig. 1, according to one embodiment of the present invention.
Detailed Description
Embodiments of the present invention relate to AHF and REC devices or drivers and methods of operation thereof for filtering harmonics present in the power input of an ASD and controlling the regenerated energy output from the ASD. The AHF and REC apparatus includes an inverter and a controller configured to operate the inverter in an AHF mode and an REC mode. The controller causes the inverter to operate in an AHF mode to filter out harmonics at the ASD input. If the ASD begins to output regenerated energy to the AHF and REC circuits, the control system causes the inverter to operate in the REC mode to direct the output back to the power input.
Referring now to fig. 1, an electrical system 10 is shown in accordance with one embodiment of the present invention. The electrical system 10 includes a power supply 12, an ASD14, and an AHF and REC device or drive 16. The power supply 12 is a three-phase power supply. Each phase 18, 20, 22 of the power supply 12 is powered by an AC power source 24 and has an inductance LSIs shown by source inductor 26. In some embodiments, the power source 12 is a utility grid. However, the power source 12 may be in the form of another type of power source, such as an energy storage device or a generator. The power supply 12 will include a source voltage vSAnd source current iSTo the ASD 14.
The ASD14 includes a housing 28 having an ASD input 30 coupled to each phase 18, 20, 22 of the power supply 12 and receiving a line current iL. Within the housing 28, an ASD input 30 is coupled to an AC line reactor 32. The line reactors 32 are shown as three inductors 34, each having a line inductance LacAnd to one of the phases 18, 20, 22 of the power supply 12. In some embodiments of the present invention, the substrate is,each inductor 34 is of more than one inductor and a total line inductance LacThe inductor group of (1). The ASD14 also includes a three-phase rectifier bridge 36 coupled to the line reactors 32. The rectifier 36 includes an arrangement of six diodes 38 for converting AC power from the line reactor 32 to DC power. The DC power from the rectifier 36 is received by a DC link 40, the DC link 40 having a positive bus 42 and a negative bus 44 with a DC link voltage v thereondc. The DC link 40 is coupled to the regenerated energy output 46, the capacitor bank 48, and the DC side 50 of the ASD inverter 52. The capacitor bank 48 has a capacitance CdcAnd may include one or more capacitors. In an exemplary embodiment, inverter 52 includes a series of Insulated Gate Bipolar Transistor (IGBT) switches and anti-parallel diodes (not shown) that collectively form a Pulse Width Modulation (PWM) inverter that is capable of inverting the DC power on its DC side 50 to AC power on AC side 53 and converting the AC power on AC side 53 to DC power on DC side 50. The AC side 53 of the inverter 52 is coupled to an ASD input/output (I/O)54 of the housing 28.
In various embodiments, the ASD14 may not include a line reactor 32, but rather one or more DC chokes. As one non-limiting example, the ASD14 may include an inductance L on the positive bus 42 of the DC link 40 between the rectifier 36 and the capacitor bank 48dcAnd an inductance L on the negative bus 44 of the DC link 40 between the rectifier 36 and the capacitor bank 48dcThe second DC choke of (1). As another non-limiting example, the ASD14 may include only one of a first DC choke on the positive bus 42 and a second DC choke on the negative bus 44. Further, in some embodiments, ASD14 may not include line reactors 32 or DC chokes.
When the ASD14 is operating under normal conditions, the DC link 40 delivers DC power thereon to the capacitor bank 48 and the inverter 52, and the inverter 52 delivers AC power to the ASD I/O54 in the enclosure 28. An AC motor 56 coupled to the ASD I/O54 receives AC power and operates to power a load (not shown). When the ASD14 is operating in a regenerative condition, i.e., when the motor 56 transfers AC power back to the ASD I/O54, the inverter 52 receives the AC power and converts it to DC power on the DC link 40. Since the rectifier 36 is only used to convert AC power to DC power and not to convert AC power to DC power, the DC link 40 transfers the DC power received from the inverter 50 to the regenerative energy output 46, even under regenerative energy conditions, the regenerative energy output 46 being coupled to the AHF and REC devices 16, as described in detail below.
The AHF and REC device 16 includes a housing 58 and a regenerated energy input 62, where the housing 58 has an I/O60 contacting each phase 18, 20, 22 of the power supply 12 and the regenerated energy input 62 is coupled to the regenerated energy output 46 of the ASD 14. The I/O60 is coupled to a first end 66 of an AC filter reactor 64. Filter reactors 64 are shown as three filter inductors 68, each having a filter inductance LacAnd to one of the phases 18, 20, 22 of the power supply 12. In other embodiments, each inductor 68 is a capacitor including more than one inductor and having a total inductance LFThe inductor group of (1). Filter inductor LFMay or may not be equal to the line inductance Lac. Further, in some embodiments, the filter inductors 64 are positioned outside of the housing 58, depending on the size requirements of the filter inductors 64.
A second end 70 of the filter reactor 64 is coupled to an AC side 74 of the AHF and REC inverter 72. Having a filter voltage v associated therewithAFFlows between the second end 70 of the filter reactor 64 and the AC side 74 of the inverter 72. Inverter 72 includes six pairs 76 of IGBT switches 78 and anti-parallel diodes 80 that together form a PWM inverter capable of converting AC power on AC side 74 to DC power on DC side 82 thereof and inverting DC power on DC side 82 to AC power on AC side 74. The DC side 82 of the inverter 72 is coupled to a DC link 83, the DC link 83 having a positive bus 85 and a negative bus 87 with a DC link voltage v thereonD. The DC link 83 is coupled to a DC capacitor bank 84 and a diode 86. The capacitor bank 84 has a capacitance CDAnd may include one or more capacitors coupled to diode 86 and REC input 62. The capacitor bank 84 may be considered an energy storage element. Diode 86 includes a cathode at a first end 88 thereof and a cathode at a first end thereofAn anode on the two end 90, with the cathode coupled to the inverter 72 and the DC side 82 of the capacitor bank 84, and the anode coupled to the regenerative energy input 62.
The AHF and REC device 16 also includes a control system or controller 92 that is constructed or programmed to control the inverter 72 and a plurality of sensors 96, 98, 100, 102, 103 that provide various measurements to the controller 92. The sensors 96, 98, 100, 102, 103 include a supply voltage sensor 96, a filtered current sensor 98, a first DC-link voltage sensor 100, a line current sensor 102, and a second DC-link voltage sensor 103, each of which measures or senses a different voltage or current. The supply voltage sensor 96 measures the supply voltage v from the power supply 12S(ii) a Filter current sensor 98 measures filter current i between filter reactor 64 and inverter 72F(ii) a The first DC-link voltage sensor 100 measures the DC-link voltage v of the DC-link 40 of the ASD14dc(ii) a Line current sensor 102 measures line current i flowing into ASD input 30L(ii) a And the second DC-link voltage sensor 103 measures the DC-link voltage v of the DC-link 83 of the AHF and REC device 16D. Each of supply voltage sensor 96, filtered current sensor 98, first DC-link voltage sensor 100, line current sensor 102, and second DC-link voltage sensor 103 may include one or more sensors to measure their respective voltages and currents as desired.
The AHF and REC device 16 also includes an optional electromagnetic interference (EMI) filter 104. The EMI filter 104 may be included in the AHF and REC device 16 to reduce switching noise generated by the inverter 52 of the ASF 14 and/or the inverter 72 of the AHF and REC device 16. The EMI filter 104 is a passive RC filter having three parallel branches of a resistor bank 106 and a capacitor bank 108 in series, and may be considered a first order high pass filter. However, in other embodiments, the EMI filter 104 may have a different configuration. Each resistor group 106 may include a resistor having a total resistance RcAnd each capacitor bank 108 may include a capacitor having a total capacitance CfThe one or more capacitors of (a). The resistor bank 106 may be formed of compact resistors and the capacitor bank 108 is smaller than the capacitor bank 48 and the electricity of the ASD14A group of containers 84. The resistor bank 106 may be considered a damping resistor that reduces the quality factor Q in the electrical system 10 in order to eliminate oscillations.
The EMI filter 104 may be selectively coupled to a node 112 between the I/O60 and the first end 66 of the filter reactor 68 by a set of relays 114, the relays 114 operable in a closed or on state and an open or off state. In embodiments including the EMI filter 104, the controller 92 is configured to control the relay 114. The controller 92 may be constructed or programmed to switch the relay 114 from an off state to an on state with an undesirable level of EMI under various conditions, such as when the switching frequency of the inverter 52 of the ASD14 or the inverter 72 of the AHF and REC devices 16 is equal to or above a predetermined or preset switching frequency threshold. As one non-limiting example, the controller 92 may cause the relay 114 to operate in a conductive state when the switching frequency of the inverter 52 or the inverter 72 is equal to or higher than 10 kHz.
The controller 92 is configured to control the inverter 72 in an on state and an off state. The controller 92 may operate the inverter 72 in the on state using two different modes: AHF mode and REC mode. If neither the AHF nor the REC mode is required, the controller 92 maintains the inverter 72 in the OFF state. When the power supply 12 is supplying power to the ASD14, the controller 92 will cause the inverter 72 to operate in AHF mode, with line current iLOr in the off state. If the ASD14 outputs regenerated energy generated by the motor 56, the controller 92 will cause the inverter 72 to operate in the REC mode to control and direct the regenerated energy back to the power source 12. When inverter 72 is operated in any of the AHF mode, REC mode, and off state, controller 92 may operate relay 114 in the on state to connect EMI filter 104 to node 112.
Referring now to fig. 2-4 and with renewed reference to fig. 1, schematic diagrams of equivalent circuits 116, 118, 120 of the electrical system 10 are shown, according to one embodiment of the present invention. Equivalent circuit 116 of FIG. 2 shows electrical system 10 when controller 92 causes inverter 72 to operate in AHF mode. Equivalent circuit 118 of fig. 3 shows electrical system 10 when controller 92 causes inverter 72 to operate in the REC mode. Equivalent circuit 120 shows electrical system 10 when controller 92 controls inverter 72 in the off state. For clarity, the housing 28 of the ASD14 and the housing 58 of the AHF and REC device 16, the controller 92, and the sensors 96, 98, 100, 102, 103 are not shown in fig. 2-4.
Referring to fig. 2, the power supply 12 supplies power to the ASD14 to drive the motor 56 in the equivalent circuit 116. Since the electric machine 56 is not generating regenerative energy, the ASD14 is operating normally, and the diode 86 (fig. 1) of the AHF and REC device 16 prevents current from flowing between the DC link 40 of the ASD14 and the DC link 83 of the AHF and REC device 16. This corresponds to the absence of a connection between the DC link 40 and the DC link 83. Thus, the diode 86 and the connection between the DC link 40 and the DC link 83 are not shown in the equivalent circuit 116 of fig. 2.
In order for the diode 86 to block the current between the DC-link 40 and the DC-link 83, the DC-link voltage v on the DC-link 83DMust be higher than the DC link voltage v on the DC link 40dc. When inverter 72 operates in AHF mode, controller 92 ensures DC link voltage vDHigher than DC link voltage vdc. The controller 92 senses the DC-link voltage v using the second DC-link voltage sensor 103DAnd converting the DC link voltage vDAdjusted to a predetermined AHF voltage. When the controller 92 causes the inverter 72 to operate in the AHF mode, the AHF voltage is set to a value that ensures that the AHF and REC device 16 are functioning properly.
Further, as a non-limiting example, the controller 92 causes the inverter 72 of the AHF and REC circuit 16 to operate in the AHF mode because the THD at the ASD input 30 of the ASD14 is above a predetermined or preset THD threshold, such as 15%, 10%, 5%, or 3%. The THD threshold is set according to the requirements of the application and/or location in which the ASD14 is implemented, as different applications and countries may require a lower THD than other applications and countries. In AHF mode, the controller 92 operates the inverter 72 to filter out the line current i present at the ASD input 30LHarmonic in (c). Harmonic is supplied by the rectifier 36 of the ASD14 on-line current iLBecause the rectifier 36 does not draw a sinusoidal current to match the supply voltage v of the power supply 12SThe sinusoidal waveform of (a). Thus, the rectifier36 make the line current iLAnd may produce over 30% THD at the ASD input 30. In many applications, such THD levels are unacceptable. Thus, as a non-limiting example, the controller 92 is configured to reduce the THD level to a target value, such as 15%, 10%, 5%, or 3%. Similar to the setting of the THD threshold, the target THD will be set according to the application of the ASD14 and/or the location where the application will be executed.
To counteract line current iLOf the line current i, the controller 92 monitors the line current i at any given momentLAnd injects the opposite or inverse harmonics of those harmonics into the loop current I through the I/O60 (fig. 1) of the housing 58 using the inverter 72L. The injection of the inverse harmonic cancels the line current iLHarmonic in (c). The controller 92 monitors the line current iLAnd determines the injection line current i based on measurements taken by the supply voltage sensor 96, the filtered current sensor 98 and the line current sensor 102LThe corresponding current in (1). The controller 92 may monitor and cancel the line current iLMedium harmonics until a certain harmonic, such as the 50 th harmonic, is reached. By doing so, as one non-limiting example, the controller 92 decreases the source current iSAnd may provide additional benefits such as power factor correction. In addition, the controller 92 may activate the EMI filter 104 to cancel the switching frequency of the inverter 52 of the ASD14 and/or the inverter 72 of the AHF and REC device 16.
Referring to fig. 3, the electric machine 56 generates regenerative energy in an equivalent circuit 118. The regenerative energy generated by the electric machine 56 results in a DC link voltage vdcAnd (4) increasing. Once DC link voltage vdcHigher than DC link voltage vDCurrent will begin to flow from the ASD14 to the AHF and REC device 16. More specifically, when the ASD14 is in a regenerative energy condition, current flows from the DC link 40 through the ASD output 46 of the enclosure 28 (fig. 1), the I/O62 of the enclosure 58, and the diode 86 to the DC link 83. Since the rectifier 36 cannot operate in the opposite direction (i.e., the rectifier 36 cannot convert the DC link voltage v)dcConverted to AC voltage) so current no longer flows through the rectifier 36 to the line reactor 32. Since the rectifier 36 is non-conductive under regenerative conditions, of FIG. 3The equivalent circuit 118 does not include the line reactor 32 or the rectifier 36.
The controller 92 may use one or more methods to determine whether the ASD14 is in a regeneration condition. The controller 92 monitors the DC-link voltage v using the first DC-link voltage sensor 100dcTo determine the DC link voltage vdcWhether the first regeneration voltage threshold has been reached or exceeded. The controller 92 may also monitor the DC link voltage v using the DC link voltage sensor 103DTo determine the DC link voltage vDWhether the second regeneration energy threshold has been reached or exceeded. Further, the controller 92 may use the first and second DC- link voltage sensors 100 and 103 to measure the DC-link voltage vdcAnd DC link voltage vDMaking a comparison to determine the DC link voltage vdcAnd a DC link voltage vDWhether the difference between is equal to or greater than the DC link voltage difference threshold.
Since the ASD14 directs regenerative energy from the electric machine 56 to the AHF and REC device 16, the controller 92 causes the inverter 72 to operate in the REC mode. The controller 92 detects that the ASD14 is in a regeneration condition using the first DC-link voltage sensor 100 and/or the second DC-link voltage sensor 103 (fig. 1). When the first DC-link voltage sensor 100 senses the DC-link voltage vdcEqual to or higher than the first regeneration voltage threshold, the second DC-link voltage sensor 103 senses the DC-link voltage vDEqual to or higher than the second regeneration voltage threshold, or when the DC-link voltages v sensed by the first and second DC- link voltage sensors 100 and 103dcAnd a DC link voltage vDWhen the difference between is greater than the DC link voltage difference threshold, the controller 92 switches to the REC mode. When in the REC mode, the controller 92 operates the inverter 72 to direct power back to the power supply 12 so that regenerated energy is not wasted. The controller 92 directs power back to the supply voltage vSAs measured by supply voltage sensor 96. In other words, the controller 92 controls the inverter 72 such that the voltage output of the first end 66 of the filter reactor 64 is equal to the supply voltage vSAnd (4) outputting the voltage.
Further, the controller 92 may optionally couple the REC filter 104 to the node 112 in the REC mode by switching the relay 114 to a conductive state. However, since the controller 92 controls the output to the power supply 12 through the inverter 72, it is generally not necessary to connect the EMI filter to the node 112 in the REC mode. Thus, in some embodiments, whenever the controller 92 causes the inverter 72 to operate in the REC mode, the controller 92 may be configured not to switch the relay 114 to a conductive state.
Referring to fig. 4, the power supply 12 supplies power to the ASD14 to drive the motor 56 in the equivalent circuit 120 in a manner similar to that shown in fig. 2. Since the electric machine 56 is not generating regenerative energy, the ASD14 is operating normally and the diode 86 of the AHF and REC device 16 prevents current from flowing between the DC link 40 of the ASD14 and the DC link 83 of the AHF and REC device 16. Thus, diode 86 prevents a connection from being established between DC link 40 and DC link 83. However, unlike fig. 2, fig. 4 shows a line current iLIs not equal to or above the THD threshold. Thus, the controller 92 need not operate the inverter 72 in either the AHF mode or the REC mode. Thus, the controller 92 controls the inverter in the off state and no current flows from the power supply 12 into the first end 66 of the filter reactor 64 (fig. 1). Since no current flows into the filter reactor 64 or the diode 86, the equivalent circuit 120 of fig. 4 does not include any components of the AHF and REC circuits 16 electrically connected between the node 112 (fig. 1) and the DC link 40 of the ASD 14. More specifically, the filter reactor 64, the inverter 72, the capacitor bank 84, and the diode 86 are not shown in fig. 4.
Controller 92 continuously monitors sensors 96, 98, 100, 102, 103 while controlling inverter 72 in the off state to monitor the state of the various measured voltages and currents. As a non-limiting example, the controller 92 may continuously determine whether the THD at the ASD input 30 of the ASD14 rises to or above the THD threshold, and the DC link voltage vdcWhether it rises to or above the regeneration voltage threshold. The controller 92 may also determine whether to activate the optional EMI filter 104. When inverter 72 is in the off state, inverter 52 of ASD14 will still be operating. Accordingly, an EMI filter 104 may be required to reduce the switching noise generated by the inverter 52.
Although controller 92 typically controls the inversionWhile the controller 72 is in the off state, the controller 92 may also be configured to keep the inverter 72 in the off state when neither the AHF mode nor the REC node is required, rather than having the inverter operate in the AHF mode. As one non-limiting example, if using ASD14 in an application does not require a reduction in THD caused by rectifier 36, controller 92 may be configured to never cause inverter 72 to operate in AHF mode. In this case, the DC link voltage vdcEqual to or above the regeneration voltage threshold and would otherwise place inverter 72 in an off state, controller 92 would cause inverter 72 to operate in the REC mode. Thus, the configuration of the controller 92 is well suited for the application of the ASD 14.
Referring now to fig. 5 and with renewed reference to fig. 1, a technique 122 for controlling the AHF and REC apparatus 16 of the electrical system 10 is illustrated according to an exemplary embodiment, as performed by a controller in the AHF and REC apparatus 16 or a controller associated with the AHF and REC apparatus 16, such as the controller 92. The process 140 begins at step 124 when power is input to the ASD14 from the power source 12, such as at startup of the ASD 14. At step 126, the controller 96 determines whether the presence of line current i needs to be filtered outLHarmonic in (c). If the THD at the ASD input 30 of the ASD14 is less than the THD threshold, the controller 92 proceeds to step 128 where the controller maintains the inverter 72 in the off state.
In embodiments that include the EMI filter 104, the controller 92 proceeds to optional steps 130, 132. Otherwise, the controller 92 proceeds directly to step 134. At step 130, the controller determines whether to activate the EMI filter 104. If the switching frequency of inverter 52 or inverter 72 is equal to or above the switching frequency threshold, the controller 92 proceeds to step 132 and switches the relay 114 from the off state to the on state to connect the EMI filter 104 to the node 112. If the switching frequency of inverter 52 and inverter 72 is below the switching frequency threshold, controller 92 proceeds to step 134 and determines if ASD14 is in a regenerated energy condition. If the DC link voltage vdcDC link voltage v less than a first regeneration voltage thresholdDLess than a second regenerative voltage threshold, or if the DC link voltage vdcAnd a DC link voltage vDThe difference therebetween is less than the DC link voltage difference threshold and the controller 92 returns to step 126.
Referring again to step 126, if the controller 92 determines that the THD at the ASD input 30 is equal to or above the THD threshold, the controller 92 proceeds to step 136 and operates the inverter 72 in AHF mode. In embodiments that include the EMI filter 104, the controller 92 proceeds to optional steps 138, 140. Otherwise, the controller 92 proceeds directly to step 134. At step 138, the controller determines whether to activate the EMI filter 104. If the switching frequency of inverter 52 or inverter 72 is equal to or above the switching frequency threshold, controller 92 proceeds to step 140 and switches relay 114 from the off state to the on state to connect EMI filter 104 to node 112. If the switching frequency of inverter 52 and inverter 72 is below the switching frequency threshold, controller 92 proceeds to step 134 and determines if ASD14 is in a regenerated energy condition. If the DC link voltage vdcDC link voltage v less than a first regeneration voltage thresholdDLess than a second regenerative voltage threshold, or if the DC link voltage vdcAnd a DC link voltage vDThe difference therebetween is less than the DC link voltage difference threshold and the controller 92 returns to step 126.
Referring again to step 134, if the DC link voltage vdcEqual to or greater than a first regeneration voltage threshold, the DC link voltage vDEqual to or greater than the second regenerative voltage threshold, or if the DC link voltage vdcAnd a DC link voltage vDThe difference therebetween is equal to or greater than the DC link voltage difference threshold, the controller 92 proceeds to step 142 and causes the inverter 72 to operate in the REC mode. In embodiments that include the EMI filter 104, the controller 92 proceeds to optional steps 144, 146. Otherwise, the controller 92 proceeds directly to step 148. At step 144, the controller determines whether to activate the EMI filter 104. If the switching frequency of inverter 52 or inverter 72 is equal to or above the switching frequency threshold, controller 92 proceeds to step 146 and switches relay 114 from the off state to the on state to connect EMI filter 104 to node 112. If the switching frequency of inverter 52 and inverter 72 is lowAt the switching frequency threshold, the controller 92 proceeds to step 148 and determines whether the ASD14 is in a regenerated energy condition. If the DC link voltage vdcStill equal to or greater than the regeneration voltage threshold, at step 142, controller 92 continues to operate inverter 72 in the REC mode. If the DC link voltage vdcLess than the regeneration voltage threshold, the controller 92 returns to step 126.
The controller 92 will continue to follow the process 122 of fig. 5 until the ASD14 is shut down. In this manner, depending on the configuration of the controller 92, THD in the electrical system 10 will be improved and the regenerative energy generated by the motor 56 will be appropriately controlled back to the power source 12. However, as noted above, the process 122 may be modified according to the particular needs of the application using the ASD 14. As one non-limiting example, in the event that THD is not a point of interest or requirement for a particular application or location, the controller 92 may be configured not to perform steps 126, 136, 138, 140 of the process 122, and instead the controller 92 will proceed directly from steps 124, 134 to step 128. In other words, the controller 92 will not determine whether to eliminate the presence of the line current iLWill keep the inverter 72 in the off state unless the controller 92 detects regenerative energy on the DC link 40.
Accordingly, embodiments of the present invention advantageously provide an AHF and REC device that combines the ability to filter out input ASD and control regenerative energy generated by a motor coupled to the ASD. The AHF and REC devices include an inverter and a controller that operates the inverter based on measurements made by a plurality of voltage and current sensors. When THD at the ASD input is equal to or above a predefined THD threshold, the controller causes the inverter to operate in AHF mode to cause THD to fall below the THD threshold. The controller causes the inverter to operate in the REC mode to control the regenerative energy output of the ASD and to return the regenerative energy to the power supply that powers the ASD when the DC link voltage in the ASD is equal to or higher than the first regenerative voltage threshold, the DC link voltage in the AHF and REC devices is equal to or higher than the second regenerative voltage threshold, or if a difference between the DC link voltage of the ASD and the DC link voltage of the AHF and REC devices is greater than the DC link voltage difference threshold. In some embodiments, the AHF and REC devices may also include EMI filters to reduce switching noise. The AHF and REC devices provide a compact and cost effective solution to filter out harmonics and control regenerative energy in the ASD, and can be coupled to the ASD as a retrofit drive. In fact, the AHF and REC devices can provide a solution where the size of the hardware is half that of the previous solution, requiring separate drivers for harmonic filtering and controlling the regenerated energy.
According to one embodiment of the present invention, an AHF and REC apparatus for an ASD includes an inverter and a control system operatively coupled to the inverter to selectively control operation thereof. The control system is programmed to: operating the inverter in an AHF mode to filter out harmonics present at the input of the ASD; and operating the inverter in the REC mode to control the regenerative energy flowing from the ASD into the inverter.
According to another embodiment of the present invention, a method of operating an AHF and REC apparatus that is coupleable to an ASD and has control thereof is performed by a controller. The method comprises the following steps: monitoring harmonics at an input of the ASD; operating the AHF and REC devices in an AHF mode to filter out harmonics; determining the flow of regenerative energy from the ASD into the AHF and REC devices; and switching operation of the AHF and REC device from the AHF mode to the REC mode to manage regenerated energy.
According to another embodiment of the present invention, a retrofit drive having an AHF and an REC for an ASD includes: a driver input/output capable of receiving a power input and releasing a power output; and a filter reactor having one or more inductors coupled to the driver input/output. The retrofit drive further comprises an inverter having an AC side and a DC side, wherein the AC side is coupled to the drive input/output through the reactor. The retrofit drive further comprises: a capacitor bank comprising one or more capacitors coupled to the DC side of the inverter; and a diode having a cathode and an anode, wherein the cathode is coupled to the capacitor bank. The retrofit driver further comprises a driver input coupled to an anode of the diode and capable of receiving the regenerated energy; further, the retrofit drive includes a controller configured to: operating the inverter in an AHF mode to filter out harmonics present at the input of the ASD; operating the inverter in an REC mode to regulate regenerative energy flowing into the driver input and into the anode of the diode; and deactivating the inverter in case the driver input does not receive regenerated energy and the harmonics present at the driver input/output are characterized by being below a preset threshold.
The present invention has been described in terms of the preferred embodiment, and it is recognized that equivalents, alternatives, and modifications, aside from those expressly stated, are possible and within the scope of the appending claims.

Claims (20)

1. An Active Harmonic Filter (AHF) and Regenerative Energy Control (REC) apparatus for an Adjustable Speed Drive (ASD), the AHF and REC apparatus comprising:
an inverter; and
a control system operatively coupled to the inverter to selectively control operation thereof, the control system programmed to:
operating the inverter in an AHF mode so as to filter out harmonics present at the input of the ASD; and is
Operating the inverter in an REC mode to control regenerative energy flowing from the ASD into the inverter.
2. The AHF and REC device of claim 1, wherein the control system is further programmed to cause the inverter to operate in an off state when the characteristic of the harmonic is below a threshold and the DC link voltage of the ASD is below a regeneration energy threshold.
3. The AHF and REC device of claim 2, wherein the harmonics are characterized by a Total Harmonic Distortion (THD) caused by the harmonics.
4. The AHF and REC device of claim 1, further comprising:
a reactor comprising one or more inductors, the reactor having a first end and a second end, the second end coupled to an Alternating Current (AC) side of the inverter;
a capacitor bank comprising one or more capacitors coupled to a Direct Current (DC) side of the inverter; and
a diode having a first end coupled to the capacitor bank and the DC side of the inverter.
5. The AHF and REC device of claim 4, further comprising a plurality of sensors, the plurality of sensors comprising:
a first sensor configured to measure a voltage of the first end of the reactor;
a second sensor configured to measure a filter current flowing between the second end of the reactor and the AC side of the inverter;
a third sensor configured to measure line current flowing into the ASD;
a fourth sensor configured to measure a DC link voltage in the ASD; and
a fifth sensor configured to measure a voltage across the capacitor bank;
wherein the control system is programmed to operate the inverter in the AHF mode and the REC mode based on the voltage and current measured by the first sensor, the second sensor, the third sensor, the fourth sensor, and the fifth sensor.
6. The AHF and REC device of claim 4, wherein the first end of the diode comprises a cathode and the second end of the diode comprises an anode.
7. The AHF and REC device of claim 4, wherein the AHF and REC device further comprises a housing, and the AHF and REC device is coupleable to an ASD as a retrofit drive.
8. The AHF and REC device of claim 7, wherein the reactor is positioned outside the housing, and the inverter, capacitor bank, diode, and control system are positioned inside the housing.
9. The AHF and REC device of claim 4, further comprising:
an electromagnetic interference (EMI) filter coupled to the first end of the reactor; and
at least one relay positioned between the EMI filter and the first end of the reactor;
wherein the control system is programmed to operate the at least one relay in an on state and an off state to selectively couple the EMI filter to the first end of the reactor.
10. The AHF and REC device of claim 9, wherein the control system is programmed to cause the at least one relay to operate in the on state if a switching frequency of an inverter of the ASD is equal to or above a predetermined threshold.
11. A method of operating an Active Harmonic Filter (AHF) and Regenerative Energy Control (REC) device that is coupleable to an Adjustable Speed Drive (ASD) and has a controller, the method performed by the controller and comprising:
monitoring harmonics at an input of the ASD;
operating the AHF and REC devices in an AHF mode to filter out harmonics;
determining that regenerated energy flows from the ASD into the AHF and REC devices; and
switching operation of the AHF and REC devices from the AHF mode to an REC mode to manage the regenerated energy.
12. The method of claim 11, further comprising:
determining that regenerative energy has stopped flowing into the AHF and REC devices; and
switching operation of the AHF and REC apparatus from the REC mode to one of the AHF mode and a non-operational mode upon determining that regenerated energy has stopped flowing into the AHF and REC apparatus, switching the AHF and REC apparatus to the AHF mode if a Total Harmonic Distortion (THD) associated with the monitored harmonic is above a predetermined THD threshold, and switching to the non-operational mode if the THD associated with the monitored harmonic is below the predetermined THD threshold.
13. The method of claim 11, wherein the AHF and REC device comprises a reactor, a capacitor bank, an inverter, and a diode, the inverter having an Alternating Current (AC) side coupled to the reactor and a Direct Current (DC) side coupled to the capacitor bank, and the diode being coupled to the capacitor bank and the DC side of the inverter; and is
Wherein when operating the AHF and REC devices in the AHF mode and the REC mode, the method further comprises selectively operating the inverter to filter out the harmonics or manage the regenerated energy.
14. The method of claim 11, wherein determining that regenerative energy flows into the AHF and REC device comprises:
measuring a voltage on a DC link of the ASD; and
determining that the DC link voltage is equal to or greater than a regeneration voltage threshold.
15. The method of claim 11, further comprising selectively activating electromagnetic interference (EMI) filters of the AHF and REC devices via a set of relays.
16. A retrofit drive having an Active Harmonic Filtering (AHF) and Regenerative Energy Control (REC) arrangement for an Adjustable Speed Drive (ASD), the retrofit drive comprising:
a driver input/output capable of receiving a power input and releasing a power output;
a filter reactor comprising one or more inductors coupled to the driver input/output;
an inverter having an Alternating Current (AC) side and a Direct Current (DC) side, the Alternating Current (AC) side coupled to the driver input/output via the reactor;
a capacitor bank comprising one or more capacitors coupled to the DC side of the inverter;
a diode having a cathode and an anode, the cathode coupled to the capacitor bank;
a driver input coupled to the anode of the diode and capable of receiving regenerative energy; and
a controller configured to:
operating the inverter in an AHF mode to filter out harmonics present at an input of the ASD;
operating the inverter in an REC mode to regulate regenerated energy flowing into the driver input and into the anode of the diode; and is
Deactivating the inverter if the driver input does not receive regenerated energy and the harmonics present at the driver input/output are characterized by being below a preset threshold.
17. The retrofit driver of claim 16, further comprising an electromagnetic interference (EMI) filter selectively coupled to a node between the driver input/output and the reactor via at least one relay operable by the controller in a closed state and an open state.
18. The retrofit driver of claim 17, wherein the controller is configured to cause the at least one relay to operate in the open state unless a switching frequency of the ASD inverter rises above a preset threshold.
19. The retrofit driver of claim 16, wherein the controller is further configured to detect regenerated energy flowing into the driver input when a voltage on a DC link coupled to the DC side of the inverter rises above a preset threshold.
20. The retrofit driver of claim 16 wherein the harmonics present at the driver input/output are characterized by Total Harmonic Distortion (THD) caused by the harmonics.
CN201910652610.2A 2018-08-01 2019-07-18 Active harmonic filter and regenerative energy control device and method of operating the same Pending CN110797880A (en)

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WO2008064716A1 (en) * 2006-11-28 2008-06-05 Baumüller Nürnberg GmbH Active brake unit
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CN113595512A (en) * 2020-08-09 2021-11-02 深圳市汇顶科技股份有限公司 High linearity low noise amplifier
CN113595512B (en) * 2020-08-09 2023-12-08 深圳市汇顶科技股份有限公司 High linearity low noise amplifier

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